A DFR Data Based Expert System For Traction Substation Fault Analysis

Modem railway is characterized by its trend of high speed and heavy duty, which demands more emphases on the reliability and security of traction power supply system and less MTTR on the event of fault. Therefore, it's theoretically sound and practically feasible to develop an expert system for traction substation fault analysis serving as an aid to operator in understanding the information conveyed by fault waveform, diagnosing faulted electrical equipments and assessing the behavior of protective relays and circuit breakers.On the basis of having a good knowledge of works previously donned by others in this field, it is illustrated in the first place that the role played by DFR (Digital Fault Recorder) Data in carrying out fault analysis should be attached enough importance. Then, the DFR system as well as its file format is introduced in comparison with COMTRADE file format from IEEE. The detailed function analysis, top level design and implementation algorism of the ES is proposed, which consists of fault information preprocessing subsystem and expert system kernel. The former is responsible for the graphic waveform analysis, faulted parameter and effective fault information extraction, and the latter for the diagnosis of faulted equipments and verifying the behavior of protective relays and circuit breakers. The expert system kernel takes the form of a typical Production Expert System: inference engine as the central part, electrical equipment database, fault information database, current jump event identification rule base, protective relaying scheme rule base and relay-CB configuration rule base as basis part, explanation module and human-machine interfacing module as assistant part. The equipments in electrical equipment database are described by means of objects, where the rules described by means of Production Rules. The procedural inference engine and the fault data driven foreword reasoning are employed. Finally, the building of tractionsubstation-related knowledge, including electrical equipment data, protective relaying scheme rule and relay-CB configuration rule, is showed in a case study, and the program of DFR data based ES for traction substation fault analysis is developed using object-oriented programming technology.